docs/ci: selfhost bootstrap/exe-first workflows; add ny-llvmc scaffolding + JSON v0 schema validation; plan: unify to Nyash ABI v2 (no backwards compat)

tools/validate_mir_json.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+"""
+Validate a MIR JSON file against the Nyash JSON v0 schema.
+
+Usage:
+  python3 tools/validate_mir_json.py <file.json> [--schema docs/reference/mir/json_v0.schema.json]
+
+Requires the 'jsonschema' Python package. Install via:
+  python3 -m pip install jsonschema
+"""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument('json_file', help='MIR JSON file path')
+    ap.add_argument('--schema', default='docs/reference/mir/json_v0.schema.json', help='Schema JSON path')
+    args = ap.parse_args()
+
+    try:
+        import jsonschema  # type: ignore
+    except Exception:
+        print('[schema] error: Python package "jsonschema" not found.\n'
+              'Install with: python3 -m pip install jsonschema', file=sys.stderr)
+        return 2
+
+    try:
+        with open(args.json_file, 'r', encoding='utf-8') as f:
+            data = json.load(f)
+    except Exception as e:
+        print(f'[schema] error: failed to read JSON: {e}', file=sys.stderr)
+        return 3
+
+    try:
+        with open(args.schema, 'r', encoding='utf-8') as f:
+            schema = json.load(f)
+    except Exception as e:
+        print(f'[schema] error: failed to read schema: {e}', file=sys.stderr)
+        return 4
+
+    try:
+        jsonschema.validate(instance=data, schema=schema)
+    except jsonschema.ValidationError as e:  # type: ignore
+        # Show human-friendly context
+        path = '/'.join([str(p) for p in e.path])
+        print(f'[schema] validation failed at $.{path}: {e.message}', file=sys.stderr)
+        return 5
+
+    print('[schema] validation OK')
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main())
+